1. Field of the Invention
This invention relates to methods for the production of ethylene glycol dialkyl ethers and more particularly relates to the production of ethylene glycol dialkyl ethers from reacting dialkyl ethers with ethylene glycol monoalkyl ethers in the presence of a heterogeneous anionic ion exchange resin catalyst.
2. Description of the Prior Art
Ethylene glycol dialkyl ethers, also known as glymes, have traditionally been very difficult to make by wet chemical procedures. Part of the difficulty with prior art methods has been in separating the glymes from the homogeneous product mixture that may contain a catalyst that is also desirable to recover. Glymes have utility in functional fluids such as transmission fluids and paint solvent formulations.
The compound designated as glyme (ethylene glycol dimethyl ether), which gives its name to the entire family of related compounds, has been prepared by a variety of methods. Russian Pat. No. 162,523 discloses how glyme may be made by reacting (CH.sub.3).sub.2 SO.sub.4 with sodium glycolate in an aqueous alcoholic mixture having a pH in the range from 7 to 8. Glyme may also be produced by reacting CH.sub.3 OCH.sub.2 CH.sub.2 Cl with MeO.sup.- ions in a methanolic solution at 40.degree. to 180.degree. C. according to French Pat. No. 1,567,133. Another method for making glyme in 14% yield along with ethylene glycol monomethyl ether in 17% yield is described by M. Pormale, et al. in Zh. Organ. Khim. 1 (10), 175862 (1965) in which ethylene glycol and CH.sub.2 N.sub.2 are reacted at 20.degree. C.
T. Koyano, et al. reveal how ethylene dichloride may be reacted with methanol at 200.degree. C. in the presence of Mg(OH).sub.2 or Zn(OH).sub.2, which serve as HCl scavengers, to give glyme in 85% conversion and 80% selectivity, Kogyo Kagaku Zasshi, 1971, 74(2), 203-7. U.S. Pat. No. 3,699,174 also reacts ethylene dichloride with methanol at 200.degree. C. for about six hours in the presence of ZnO to give glyme in 65.9% yield. Ethylene dichloride is again reacted with methanol for six hours from 150.degree. to 350.degree. C. as described in Japanese patent No. 75-09,764, this time in the presence of alkali earth metals manganese, iron or cobalt or their hydroxides or alkali earth alcoholates.
Ethylene is reacted with methanol and iodine in the presence of oxygen at 140.degree. to 160.degree. C. to produce mostly glyme but some methyl iodide and CH.sub.3 OCH.sub.2 CH.sub.2 I as described in Japanese Pat. No. 75-07,578. German Offenlegungsschrift No. 2,434,057 reveals that 89% glyme yield may be obtained by reacting (CH.sub.3 OCH.sub.2 CH.sub.2 O).sub.2 CH.sub.2 at 160.degree. C. over a nickel, cobalt or copper catalyst in the presence of hydrogen.
Other methods have made glyme in poor yields from alcohols and alkylene oxides. For example, M. R. Leanov and I. A. Korshunov produce mostly ethylene glycol monomethyl ether along with 5% glyme by reacting methanol with ethylene oxide at 200.degree. C. and 6 to 32 atm, Tr. po Khim. i Khim. Teknol. 1964 (3), 51520. Japanese Pat. No. 78-37,607 discloses that C.sub.2 C.sub.4 alkylene oxides reacted with various alcohols and (CH.sub.3).sub.2 CHOH at 120.degree. C. can produce ethylene glycol monomethyl ether and related products along with a small amount of glyme. It has further been discovered that the oxyalkylation of hydroxyl compounds with alkylene oxides in the presence of a sulfonated perfluorocarbon polymer resin catalyst give primarily the mono-oxyalkylated derivative, German Offlegungsschrift No. 2,917,805.
Given the low glyme yields and separation problems associated with the homogeneous systems of the prior methods, it is an object of this invention to provide a method for the production of glymes in high yield via a system using a heterogeneous catalyst that minimizes difficulties with the separation procedures.